Centering and guiding means for metal studs



June 1964 H. z. ROSENBERG, JR 3,137,195

CENTERING AND GUIDING MEANS FOR METAL STUDS Filed NOV. 20, 1961 FF 5 3F! G 4.

INVENTOR Harry 2. Rosenberg,Jr.

ATTORNEY United States Patent fiice 3,137,195 Patented June 16, 19643,137,195 CENTERING AND GUIDlNG MEANS FQR METAL STUDS Harry Z.Rosenberg, In, Miami Beach, Fla., assignor to American InternationalTool Corporation, Miami Beach, Fla, a corporation of Florida Filed Nov.20, 1961, Ser. No. 153,349 3 Claims. (Cl. 85-10) The present inventionrelates to centering and guiding means for metal studs, nails, pins andlike fastening devices which are fired into surfaces such as concrete,masonry, steel and the like, by the use of an explosively ac tuated handtool.

Heretofore, a number of centering and guiding means of this type havebeen proposed but due to their structural shapes and/ or the materialfrom which they are fabricated, they have not been found entirelysatisfactory in performance.

It has previously been considered expedient to make these members of amaterial which will be consumed due to the heat and impact of theexplosion during its travel through the tool. It has now been found thatthis type of material does not give entirely satisfactory performance.

It is therefore an object of the present invention to provide improvedcentering and guiding means of the aforesaid type which are made from aplastic material which has the characteristics of withstanding the forceof the explosion and remaining nearly intact throughout its travelthrough the tool.

It is a further object of the present invention to provide improvedcentering and guiding means of the aforesaid type which are capable ofsubstantially increasing the penetration for a given exposive chargeover those previously proposed.

It is a still further object of the present invention to provide animproved centering and guiding means which is so constructed as to beusable with various shank diameters of nails and the like.

A still further object of the present invention is to provide animproved cap for an explosively driven nail or the like which has ashape capable of increasing the penetration thereof for a givenexplosive charge.

Other objects and the nature and advantages of the pres ent inventionwill become apparent from the following description taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a view partly in section of a part of the front end portion ofthe barrel of an explosively actuated hand tool and containing in thebore thereof a fastening element, the front and rear end portions ofwhich are provided with centering and guiding members embodying thepresent invention;

FIG. 2 is a longitudinal sectional view similar to FIG. 1;

FIG. 3 is a top plan view of the front centering and guiding member; and

FIG. 4 is a sectional view of the rear centering and guiding member. Thecentering and guiding members in accordance with the present inventionare for use with various types of fastening elements, such as pins,nails, threaded studs, eyelet nails, and the like which are fired intosteel, concrete, masonry and like materials by the use of explosivelyactuated hand tools. When the term stud is used in the claims, it shouldbe understood that any of these conventional fastening elements arecontemplated.

As illustrated in FIGS. 1 and 2, a threaded stud is shown in the barrelbore 12 of an explosively actuated hand tool. The front centering andguiding element 14 is mounted on the shank portion 16 of the stud andthe rear centering and guiding element 18 is mounted on the head portion20 of the stud. These front and rear elements 14 and 18 cooperate toinsure true centering of the studs in the tool barrel bores in whichthey are used and also true guidance of the studs in their travelthrough the bores. The rear element 18 also serves the importantfunction of sealing otf the gases resulting from the explosive chargeand increasing the penetration of the stud in the hard surface intowhich it is fired.

The rear end centering and guiding member, best shown in FIG. 4, is ofgenerally cup shape with a central chamber 22 of such size as tofrictionally grip the rear head portion 20 of the stud. The length ofthe member may be varied as desired, but it should be sufficient toprovide ample contact with the tool barrel and to remain on thefastening element. The outside diameter 24 at the rear end of theelement 18 is such as to properly fit the tool barrel, and preferablythe remainder of the outside diameter 26 is of a slightly lesserdiameter than at 24 to reduce frictional contact with the barrel yet toyield a sufficient seal and guidance means.

The inside chamber 22 may be provided with small wedges or threads 28 onthe lower portion thereof. These indentations 28 provide for a bettergrip against threaded studs and also serve as a ledge for holding thehead of a nail in its proper position. A conical hole 30 is provided inthe upper wall 32 of the inside chamber 22. This hole 30 provides for anease in molding and ejection from the mold and also assists in holdingthe fastening element in the member 18.

The upper outer end of the element 18 is provided with a cup-shapeddepression 34 and the edges 36 surrounding the cup-shaped depression 34are sharp and square to provide for a better seal against the explosivegases and thus prevent them from creeping around the edges of the member18. The edges 36 are so designed in conjunction with the cup-shapeddepression 34 that the explosive force will push the edges against thewalls of the barrel maintaining an excellent seal during its travelalong the barrel.

The front centering and guiding element 14 has a circular body portion40 having a diameter intermediate between the outer diameter of theshank portion 16 of the stud 10 and the inner diameter of the barrel ofthe driving tool. A plurality of flexible inner protrusions or fins 42are provided integral with the body portion 40 and extending inwardlytherefrom. The inner ends of said inner protrusions 42 form a diameterwhich will frictionally engage the shank portion 16 of the stud. Theinner protrusions 42 are capable of bending outwardly to engage shankportions of varying diameters. Thus, for example, the same element 14can be used with shank diameters varying from inch up to inch.

The element 14 is also provided with a plurality of flexible outwardlyextending protrusions or fins 44 which are integral with the bodyportion 40. As illustrated, there are eight inner protrusions 42 andeight outer protrusions 44 in staggered arrangement about the bodyportion 40. The outer diameter of the ends of the outer protrusions 44is such that they contact the barrel of the driving tool.

It should be noted that the inner and outer protrusions are so arrangedand spaced so that the bending of the inner protrusions due to a largershank diameter does not add to the pressure of the outer protrusions onthe barrel of the tool which must remain constant.

The rear centering and guiding element 18 is made of a plastic materialwhich is capable of withstanding the force and heat of the explosionwithout disintegrating and which will remain intact throughout thetravel of the stud through the tool. On the other hand, the frontcentering and guiding element 14 may be made of any plastic materialwhich can be molded or extruded into the shape illustrated and in whichthe protrusions will be flexible.

I It has been found that the only material suitable for i use as therear centering and guiding element 18 is a thermoplastic polycarbonateresin. Examples of such polycarbonate resins are Lexan, manufactured by'the .G'ener'al Electric Company, and Merlon, rnanufactured by the MobayChemical Company. The polycarbonate name is taken from the carbonatelinkage which joins the organic units in the polymer and which is anintegral part of the-main polymer chain. Such polycarbonate resins canbe made by combining a bifunctional phenol,

, bisphenol-A, with a carbonyl chloride by splitting out hydrochloricacid' to give a linear polymer consisting of V bi'sphenol groups joinedtogether by carbonate linkages as represented by the following formula:

resins, andothers. A simple testwill show :the unexpected-resultsobtained using the present polycarbonate resinrear centering and guidingelement'18 as against an element made of polyethylene. "Using a pin 2%"long with a shank diameter of Y with the polycarbonate resin rearelement, a penetration to 78" below the surface of the concrete foratotal of three inches of penetration. Using the same pin, with the samestrength explosive charge but with a polyethylene rear element, a totalpenetration of 1% inches is obtained. With heavier explosive chargeseven more spectacular results are obtained using the guide elements inaccordance with-the present invention. V

The front centering and-guiding element .14 can be extruded from a vinylresin, for example, in a continuous extrusion of the cross section shownin FIG. 3 and then cut into the desired lengths.

It should be noted that although the drawings show the rear element asseparate from the stud, it is equally. effective when the rear elementis molded ontothe stud.

fpropionate, polyethylene, nylon, polypropylene, vinyl at least aportion of said .cap generally corresponding to the size of said barrelbore, the rear end portion of said cap priorto explosion having acup-shapeddepres-Y sion in the central portion thereof surrounded bya'lip,v which is sharp and square to yield a gas seal during the travelof the element alongthe barrel, said cup-shaped I depression havingasubstantially fiat bottorn'surface there- 1 tively hard material, saidelement'having' a front guiding and'centering means retained on saidelement shank portion, said element'havinga" rear guiding and centering1 means which comprises a cap made {of a thermoplastic polycarbonateresin and being retained'over the near end of the fastening element,said cap having a hollow. central chamber, the outside diameter of atleasti a portion'of said cap generally, corresponding to the size-ofsaid barrel bore the rear end portion of fsaid. cap, prior 9 toexplosion having a cup-shaped'depi essionin the cen-' m portion thereofsurrounded by a' lip which is. sharp and square to yield a gas seal,during the travel of the element alonglthe barrel, saidcup-shapeddepression hav- 7 ing a substantially fiatbottom surface therein.

1.3. A fastening element in accordance with claim wherein said frontguiding and centering means comprises a circular body portionhavinga-diarn'eter intervmediate between the outer diameter ofthe shankportion of the element 'and the inner diameter of the barrel ofthedriving' tool, a plurality of flexible innerv protrusions integralwith said bodyportion and extending inwardly therefrom, anda pluralityof flexible'outer pro- It will be obvious to those skilled in the artthat various changes may be made withoutdeparting from the spirit,

of the invention and therefore the invention is not'limited said shankportion having a front end part tapered to' a point to facilitate theinsertion of the'element into said relatively hard material, saidelement having a rear guida thermoplastic polycarbonate resin and beingretained over the rear end of the fastening element, said cap having ahollow central chamber, the outside diameter of 'to what is shown in thedrawings and described in the? ing and centering means which comprises acap made of trusions integral with said body portion and extendingoutwardly therefrom, said body portion, inner protrusions and outerprotrusions all extending'in the same plane,.

said innerprotrusionsand said outer protrusionsbeing capable of bendingas necessary to accommodate various sizes of shanks and barrelsrespectively.

References Cited in the file of this patent I UNITED STATES PATENTS2,578,809 Ketchum" Dec. 18, 1951 2,676,508 Erickson Apr.'27, 1.9542,722,004 Webb'er 6t al.f Nov. 1, 1955, 2,761,348 Williams et al Sept.4, 1956 2,820,412 Beeuwkes et a1. Jan. 21, 1958 2,911,911 White i Nov.10, 1959 2,920,563 De Caro 'Jan. 12, 1960 2,983,224 Pros'en et al. May9, 1961 3,007,726 Palldil Nov. 7, 1961 FOREIGN PATENTS i 228,465Australia 1 Oct. 9, 1958 737,968 Great Britain Oct. 5,-1955 Y OT E -RFEREN ES Lexan Polycarbonate Resin, General Electric, Chem.

Development'Dept, April 1958 (reprinted fromv Modern Plastics Magazine,April 1958). 1

2. A fastening element for insertion into relatively hard material byits ejection through the bore of the barrel of an explosively actuateddriving tool, said element comprising a shank portion and a rear endportion, said shank portion having a front end 'parttapered to a pointto. facilitate the insertion of the element into said rela-

2. A FASTENING ELEMENT FOR INSERTION INTO RELATIVELY HARD MATERIAL BYITS EJECTIN THROUGH THE BORE OF THE BARREL OF AN EXPLOSIVELY ACTUATEDDRIVING TOOL, SAID ELEMENT COMPRISING A SHANK PORTION AND A REAR ENDPORTION, SAID SHANK PORTION HAVING A FRONT END PART TAPERED TO A POINTTO FACILITATE THE INSERTION OF THE ELEMENT INTO SAID RELATIVELY HARDMATERIAL, SAID ELEMENT HAVING A FRONT GUIDING AND CENTERING MEANSRETAINED ON SAID ELEMENT SHANK PORTION, SAID ELEMENT HAVING A REARGUIDING AND CENTERING MEANS WHICH COMPRISES A CAP MADE OF ATHERMOPLASTIC POLYCARBONATE RESIN AND BEING RETAINED OVER THE REAR